1. Technical Field
The disclosure relates to a control apparatus for a vehicle and a control method that change over a lockup clutch that is attached to a torque converter to one of a complete engagement state, a slip engagement state and a complete release state in accordance with an operating state of the vehicle.
2. Description of Related Art
In the case where an automatic transmission that combines a plurality of planetary gear trains with a plurality of frictional engagement elements is connected to an internal combustion engine for a vehicle, a torque converter is generally incorporated between this internal combustion engine and the automatic transmission. Besides, it is common to assemble a lockup clutch with the torque converter for this vehicle so that this lockup clutch can be changed over to one of a complete engagement state, a slip engagement state and a complete release state in accordance with an operating state of the vehicle. Japanese Patent Application Publication No. 2009-097603 (JP 2009-097603 A) discloses a control apparatus for a vehicle that is mounted with a torque converter to which such a lockup clutch is attached, as well as an automatic transmission. In this Japanese Patent Application Publication No. 2009-097603 (JP 2009-097603 A), when the deceleration of the vehicle is equal to or larger than a deceleration threshold, the lockup clutch is switched from an engagement state to a release state to prevent an engine from stalling. Besides, when sport running is selected as a shift mode or when an accelerator pedal is depressed, the foregoing deceleration threshold is changed to a larger value to make the lockup clutch unlikely to be switched to the release state.